Metastatic prostate cancer presenting as diplopia with regression of signs with hormone manipulation

A 73-year-old man presented with sudden onset diplopia. He was referred to the ophthalmology team who thought he had a VIth nerve palsy. He subsequently underwent computed tomography (CT) (Figure 1) and magnetic resonance imaging (Figure 2). These images revealed a mass occupying and expanding the sella with extension inferiorly to the sphenoid sinus. The clivus was almost completely replaced by tumour. The cavernous sinuses were involved bilaterally but the optic chiasm was not involved. It was thought that these finding were consistent with an unusual invasive pituitary tumour and surgical excision biopsy was undertaken. The histology was consistent with metastatic carcinoma of the prostate. His prostate-specific antigen (PSA) taken post-histology was 382 μg/litre and a bone scan confirmed metastases in the ribs, thoracic and lumbar spine, sacrum, left sacroiliac joint, ilium, ischium and pubis. He was subsequently started on luteinizing hormone-releasing hormone analogues which brought about a resoluti...